The present invention relates to integrated semiconductor circuits (ICs) and, more particularly, to a novel power supply circuit which is located on the IC chip itself for providing to the chip's circuitry at least one DC operating potential, when driven either by an AC line source or a source of DC voltage, the selected source having a potential magnitude higher than the highest DC potential to be supplied by the circuit.
It is often necessary, in a semiconductor integrated circuit, to provide a relatively low voltage DC supply with minimized parts, cost and very low standby power dissipation, regardless of whether high-voltage DC or AC potential is available as the input source. It is highly desirable to provide an on-chip DC power supply and thus eliminate necessity for providing a separate DC power supply external to the integrated circuit, which external power supply would be required, in the absence of an on-chip power supply, to provide operating potential for at least a lower-voltage portion of an IC. It is also highly desirable to provide an on-chip power supply which is flexible enough to operate over a relatively wide range of input supply voltage.